
<template>
  <div class="pagination">
      <div>{{startAndEndNum}}</div>
    <button @click="$emit('currentPage',pageNo-1)">上一页</button>
    <button :disabled="pageNo==1" v-if="startAndEndNum.start>=2" @click="$emit('currentPage',1)">1</button>
    <button v-if="startAndEndNum.start>=3">···</button>

    <button v-for="page in startAndEndNum.end"  :key="page" v-if="page>=startAndEndNum.start" :class="{active:pageNo==page}" @click="$emit('currentPage',page)">{{page}}</button>
    
    
    <button v-if="startAndEndNum.end<totalPage - 1">···</button>
    <button v-if="startAndEndNum.end<totalPage"  @click="$emit('currentPage',totalPage)">{{totalPage}}</button>
    <button @click="$emit('currentPage',pageNo+1)">下一页</button>
    
    <button style="margin-left: 30px">共 {{total}} 条</button>
  </div>
</template>

<script>
export default {
  name: 'Pagination',
    props:['total','pageSize','pageNo','continues'],
    computed:{
        totalPage(){
            return Math.ceil(this.total / this.pageSize)
        },
        //计算出连续页码数的数字（开始数字和结束数字）
        startAndEndNum(){
            const { pageNo,continues,totalPage } = this
            let start = pageNo - parseInt(continues / 2);
            let end = pageNo + parseInt(continues / 2);
            //还有一些需要纠正的特殊数字
            if(start<1){
                start = 1;
                end = continues;
            }
            if(end> totalPage){
                end = totalPage;
                start = totalPage-continues+1
            }
            //当前这个写法 需要把开始与结束返回，只能返回一个对象 KV一致省略V
            return { start,end }

        },
    }

}
</script>

<style lang="less" scoped>
  .pagination {
      text-align: center;
    button {
      margin: 0 5px;
      background-color: #f4f4f5;
      color: #606266;
      outline: none;
      border-radius: 2px;
      padding: 0 4px;
      vertical-align: top;
      display: inline-block;
      font-size: 13px;
      min-width: 35.5px;
      height: 28px;
      line-height: 28px;
      cursor: pointer;
      box-sizing: border-box;
      text-align: center;
      border: 0;

      &[disabled] {
        color: #c0c4cc;
        cursor: not-allowed;
      }

      &.active {
        cursor: not-allowed;
        background-color: #409eff;
        color: #fff;
      }
    }
  }
</style>
